As data transmission bandwidth demands increase, fiber optic cables are in increasing use in many applications. One such application of high importance is transmission of data by undersea cables.
In this setting, the pressures on electrical and/or optical connectors and cabling pose a threat to the integrity of the transmission cables. Junction regions are particularly vulnerable, such as where a high-pressure region is coupled to a low-pressure region in an undersea environment.
Some systems currently in use include a “multi-gland” fiber seal to block the passage of gases and fluids. Such seals generally have to be hand crafted and formed in matched groups with tight specifications, and are designed primarily to prevent water ingress in the event of a cable breach. Gland seals are somewhat limited in their ability to tolerate high pressure.
There is a need for a seal for undersea cables, including cable junctions, that does not need to be hand-made and is tolerant of variations in the manufacture process without compromising integrity. In particular, there is a need for such a seal that protects against the passage of both gases and liquids, and that survives high-pressure environments intact.
An advantage of the epoxy seal vis-à-vis prior sealing arrangements, such as multi-gland seals, is the ability of the seal to operate while at pressure with an optical loss of less than approximately 0.05 db. This can be achieved by the bonding of the optical fibers plating to the epoxy material, minimizing or preventing possible extrusions at high pressure, which could cause damage to the optical path.